Most modern vehicles today incorporate air bags and deployment systems. Weight drop systems are commonly employed in the automotive industry to apply a load to an automotive seat to test and calibrate air bag deployment systems. Such calibration and testing is necessary to ensure compliance with the federal motor vehicle safety standards (FMVSS). The deployment systems typically include various sensing systems, commonly known as PODS-B and Strain Gauge Occupancy sensing systems, incorporated into the automotive seat. The sensors identify the weight of the individual seated upon the seat. Based upon this sensed weight, the deployment system fires the air bag during a collision at a predetermined force. For example, such a deployment system may fire the air bag at full force for a full-sized adult but only fire the air bag at half force for a lighter adult or child. In such air bag and deployment systems, it is important that the sensors be properly calibrated and tested to accurately identify the weight of the seat occupant.
Various weight drop systems are commonly employed to drop a predetermined weight upon a vehicle seat to test and calibrate the sensors of the air bag deployment system. One known system includes a rigid rectangular frame including four linear round shafts which guide a single weight between a raised undeployed position and a deployed lowered position in which the weight applies a load to a seat. The weight is connected to a cable which is connected to a motorized winch. The motorized winch binds the cable to lift the weight to the raised position. To drop the weight, the winch is released from the cable so as to allow the weight in the cable to fall.
Although commonly employed, this known system has several drawbacks. Because the weight remains attached to the cable as the load is being applied, the inertia of the cable adds force above and beyond the calibrated weight, leading to a variance in the resulting load. In addition, the four round shafts used to guide the weight cause slight binding which introduces unwanted friction and load variations. As a result, calibration and testing accuracy is impaired. Furthermore, because the system only enables the use of a single weight, applying different weights or loads requires the redesign and modification of the system or requires the use of multiple systems to apply different loads.